Area code 423

Area code 423 is a telephone area code in the state of Tennessee, United States. It covers the eastern part of the state, including the cities of Chattanooga, Johnson City, and Kingsport. It was created on September 11, 1995 as a split from area code 615, which originally covered most of Tennessee. The new area code was introduced to handle the growing demand for more phone numbers in the eastern part of the state. It was split by 865 in 1999 and will be overlaid by 729 in 2025.